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1. Mechanical Integrity and Reinforcement Efficiency of Graphene Grown on Liquid Copper by Chemical Vapor Deposition

Author: Ilias Sfougkaris, Christos Tsakonas, Anastasios C. Manikas, Maria Giovanna Pastore Carbone, Christos Pavlou, Irene M. N. Groot, Mehdi Saedi, Gertjan J. C. vanBaarle, Marc deVoogd, Valentina Rein, Maciej Jankowski, Oleg V. Konovalov, Gilles Renaud, and Costas Galiotis
Subjects: graphene, mechanical reinforcement, Raman spectroscopy, liquid metal catalysts, Physics, QC1-999, Technology
Abstract: Abstract Graphene is a perfect 2D crystal of covalently bonded carbon atoms and constitutes the building block for all graphitic structures. Its superior properties make it an attractive material for a variety of technological applications. However, mass production does not meet the initial expectations. Chemical Vapor Deposition (CVD) is currently the only available method for large‐scale automated production, but the produced graphene sheets suffer from structural and morphological defects that degrade considerably the mechanical and other physical properties of synthesized graphene. Recently, the use of liquid metal catalysts (LMCat) has been proposed as an alternative platform for facile and high‐quality synthesis of single‐crystal graphene. Herein, simultaneous Raman spectroscopy combined with mechanical testing is adopted confirming that the reinforcing efficiency of the LMCat graphene is greatly improved. In fact, the effective Young's modulus of LMCat graphene has been found ≈630 GPa, which is significantly higher than the graphene grown on solid Cu substrate due to differences in the morphology of Cu substrate. Overall, this work paves the way for the development of defect‐free graphene of quality comparable to exfoliated flakes, and this will have a major technological impact for many applications.
Published: 2024
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2. Employing Surface Curvature for Spatially Resolved X‐Ray Reflectivity: Graphene Domains on Liquid Copper

Author: Valentina Belova, Maciej Jankowski, Mehdi Saedi, Irene M. N. Groot, Gilles Renaud, and Oleg V. Konovalov
Subjects: 2D materials, curved surfaces, graphene, imaging, liquid surfaces, synchrotron radiation, Physics, QC1-999, Technology
Abstract: Abstract Here the possibility of utilizing X‐ray reflectivity for visualization with ≈µm spatial resolution of a surface with a heterogeneous electron density due to a partial coverage by another nanometrically thin material is demonstrated. It requires the sample to be convexly bent, thus reflecting the collimated incident beam onto a magnified image recorded by a position‐sensitive detector. By the use of a small, intense, and parallel beam such as provided by the most recent synchrotron sources, one can record such spatially resolved X‐ray reflectivity with 0.1–1 kHz frame rate. The use of the method for in situ, time‐resolved characterization of single‐layer graphene domains during their chemical vapor deposition on a naturally curved surface of a liquid copper drop is demonstrated. This method can follow the growth kinetics, including the coverage ratio, 2D crystal (flake) sizes, and distances between flakes. By taking a single scan, the individual X‐ray reflectivity curves can be reconstructed, of both covered and noncovered parts of the surface, allowing to deduce the corresponding electron density profiles perpendicular to the surface. The technique has a promising perspective for in situ study of 2D materials, ultrathin films, and self‐assemblies on liquid as well as solid surfaces.
Published: 2023
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3. X-ray reflectivity from curved surfaces as illustrated by a graphene layer on molten copper

Author: Oleg V. Konovalov, Valentina Belova, Francesco La Porta, Mehdi Saedi, Irene M. N. Groot, Gilles Renaud, Irina Snigireva, Anatoly Snigirev, Maria Voevodina, Chen Shen, Andrea Sartori, Bridget M. Murphy, and Maciej Jankowski
Subjects: x-ray reflectivity, curved surfaces, methods, synchrotron, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798, Crystallography, QD901-999
Abstract: The X-ray reflectivity technique can provide out-of-plane electron-density profiles of surfaces, interfaces, and thin films, with atomic resolution accuracy. While current methodologies require high surface flatness, this becomes challenging for naturally curved surfaces, particularly for liquid metals, due to the very high surface tension. Here, the development of X-ray reflectivity measurements with beam sizes of a few tens of micrometres on highly curved liquid surfaces using a synchrotron diffractometer equipped with a double crystal beam deflector is presented. The proposed and developed method, which uses a standard reflectivity θ–2θ scan, is successfully applied to study in situ the bare surface of molten copper and molten copper covered by a graphene layer grown in situ by chemical vapor deposition. It was found that the roughness of the bare liquid surface of copper at 1400 K is 1.25 ± 0.10 Å, while the graphene layer is separated from the liquid surface by a distance of 1.55 ± 0.08 Å and has a roughness of 1.26 ± 0.09 Å.
Published: 2022
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4. Graphene at Liquid Copper Catalysts: Atomic‐Scale Agreement of Experimental and First‐Principles Adsorption Height

Author: Hao Gao, Valentina Belova, Francesco La Porta, Juan Santiago Cingolani, Mie Andersen, Mehdi Saedi, Oleg V. Konovalov, Maciej Jankowski, Hendrik H. Heenen, Irene M. N. Groot, Gilles Renaud, and Karsten Reuter
Subjects: graphene, liquid metal catalyst, machine learning, X‐ray reflectivity, Science
Abstract: Abstract Liquid metal catalysts have recently attracted attention for synthesizing high‐quality 2D materials facilitated via the catalysts’ perfectly smooth surface. However, the microscopic catalytic processes occurring at the surface are still largely unclear because liquid metals escape the accessibility of traditional experimental and computational surface science approaches. Hence, numerous controversies are found regarding different applications, with graphene (Gr) growth on liquid copper (Cu) as a prominent prototype. In this work, novel in situ and in silico techniques are employed to achieve an atomic‐level characterization of the graphene adsorption height above liquid Cu, reaching quantitative agreement within 0.1 Å between experiment and theory. The results are obtained via in situ synchrotron X‐ray reflectivity (XRR) measurements over wide‐range q‐vectors and large‐scale molecular dynamics simulations based on efficient machine‐learning (ML) potentials trained to first‐principles density functional theory (DFT) data. The computational insight is demonstrated to be robust against inherent DFT errors and reveals the nature of graphene binding to be highly comparable at liquid Cu and solid Cu(111). Transporting the predictive first‐principles quality via ML potentials to the scales required for liquid metal catalysis thus provides a powerful approach to reach microscopic understanding, analogous to the established computational approaches for catalysis at solid surfaces.
Published: 2022
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5. Prévalence du syndrome métabolique chez le patient diabétique de type 2 à Bouaké, Côte d’Ivoire

Author: Koné, Famoussa, Gnaba, Loa Ambroise, Touré, Kadidiata Hamed, Kouassi, Lauret, Koné, Salifou, Acho, Jean Kévin, Touré, Yenahaban Lazare, Kouamé, Kouamé Gilles Renaud, Yapa, Gnadou Stéphane Kény, Adoubi, Kassi Anicet, and Ouattara, Bourhaima
Published: 2024
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6. Crecimiento y características de la canal de corderos cruzados de hampshire, suffolk o southsuffolk con hembras rambouillet en el altiplano de México

Author: Jorge Urrutia M., Graciela Tapia P., Gilles Renaud, and Leonel Martínez O.
Subjects: hampshire, suffolk, southsuffolk, rambouillet, Animal culture, SF1-1100, Veterinary medicine, SF600-1100
Abstract: Se evaluaron las características de peso al nacimiento, (PN) velocidad de crecimiento predestete, peso al destete (PO) (90 días), peso ajustado a 150 días, (P150) rendimiento en canal (RC) y composición de la misma
Published: 1988

7. Superstructures, Commensurations, and Rotation of Single-Layer TaS 2 on Au(111) Induced by Cs Intercalation/Deintercalation

Author: Xiaorong Weng, Philippe David, Valérie Guisset, Lucio Martinelli, Olivier Geaymond, Johann Coraux, Gilles Renaud, Nanostructures et Rayons X (NRX), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)
Subjects: [PHYS]Physics [physics], General Engineering, General Physics and Astronomy, General Materials Science
Abstract: International audience
Published: 2023
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8. Monkeypox in an Immunocompetent Vaccined Adult: A Case Report at the University Teaching Hospital of Bouake

Author: Kone Djakaridja, Yapo Martine Tatiana, Kadiane-Oussou Juliette, Akanji Iburaima Alamun, Gue Irené, Kouabenan Amon Stéphene, Koné Famoussa, Sule Mutiyu Akanbi, Kouamé Kouamé Gilles Renaud, Karidioula Jean Marie, Aba Yapo Thomas, and Kra Ouffoue
Subjects: General Medicine
Published: 2022
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9. Real-time multiscale monitoring and tailoring of graphene growth on liquid copper

Author: Juan Santiago Cingolani, Francesco La Porta, Maciej Jankowski, Oleg Konovalov, Gertjan J. C. van Baarle, Costas Galiotis, Mie Andersen, Gilles Renaud, Irene M. N. Groot, Karsten Reuter, Mehdi Saedi, Anastasios C. Manikas, Marc de Voogd, Christos Tsakonas, Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)
Subjects: Liquid metal, Materials science, General Physics and Astronomy, Nanotechnology, 02 engineering and technology, Chemical vapor deposition, 010402 general chemistry, liquid metal catalyst, 01 natural sciences, Article, law.invention, symbols.namesake, CVD graphene, law, General Materials Science, two-dimensional materials, ComputingMilieux_MISCELLANEOUS, Atmospheric pressure, Graphene, General Engineering, radiation optical microscopy, 021001 nanoscience & nanotechnology, Multiscale modeling, self-organization, 0104 chemical sciences, X-ray diffraction, ddc:540, Raman spectroscopy, symbols, Crystallite, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, Dispersion (chemistry)
Abstract: ACS nano 15(6), 9638 - 9648 (2021). doi:10.1021/acsnano.0c10377, The synthesis of large, defect-free two-dimensional materials (2DMs) such as graphene is a major challenge toward industrial applications. Chemical vapor deposition (CVD) on liquid metal catalysts (LMCats) is a recently developed process for the fast synthesis of high-quality single crystals of 2DMs. However, up to now, the lack of in situ techniques enabling direct feedback on the growth has limited our understanding of the process dynamics and primarily led to empirical growth recipes. Thus, an in situ multiscale monitoring of the 2DMs structure, coupled with a real-time control of the growth parameters, is necessary for efficient synthesis. Here we report real-time monitoring of graphene growth on liquid copper (at 1370 K under atmospheric pressure CVD conditions) via four complementary in situ methods: synchrotron X-ray diffraction and reflectivity, Raman spectroscopy, and radiation-mode optical microscopy. This has allowed us to control graphene growth parameters such as shape, dispersion, and the hexagonal supra-organization with very high accuracy. Furthermore, the switch from continuous polycrystalline film to the growth of millimeter-sized defect-free single crystals could also be accomplished. The presented results have far-reaching consequences for studying and tailoring 2D material formation processes on LMCats under CVD growth conditions. Finally, the experimental observations are supported by multiscale modeling that has thrown light into the underlying mechanisms of graphene growth., Published by Soc., Washington, DC
Published: 2021
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10. Oxide at the Al-rich Fe0.85Al0.15(110) surface

Author: Jacques Jupille, Pascal David, Stéphane Chenot, Patrizia Borghetti, Claudine Noguera, Gregory Cabailh, Gilles Renaud, Alexey Koltsov, Natalia Alyabyeva, Jacek Goniakowski, Rémi Lazzari, Maxime Van den Bossche, and Zongbei Dai
Subjects: Diffraction, Nial, Materials science, Physics and Astronomy (miscellaneous), Alloy, Ab initio, Oxide, Analytical chemistry, 02 engineering and technology, Substrate (electronics), engineering.material, 01 natural sciences, law.invention, chemistry.chemical_compound, law, 0103 physical sciences, General Materials Science, 010306 general physics, computer.programming_language, 021001 nanoscience & nanotechnology, chemistry, Electron diffraction, engineering, Scanning tunneling microscope, 0210 nano-technology, computer
Abstract: The formation of an ultra-thin aluminum oxide film at Fe0.85Al0.15(110) surface (A2 random alloy) has been studied by a variety of surface sensitive techniques (X-ray photoemission, low-energy electron diffraction, surface X-ray diffraction and scanning tunneling microscopy) supplemented by ab initio atomistic simulations. Since iron is not oxidized in the used conditions, the study focused on the coupling between aluminum oxidation and segregation processes. Compared to the bare surface, whose average composition (Fe0.6Al0.4) is closer to the B2-CsCl structure over a ∼ 3 nm depth, the oxidation hardly affects the subsurface segregation of aluminum. All the structural and chemical fingerprints point to an oxide film similar to that found on NiAl(110). It is a bilayer (∼ 7.5A thick) with a composition close to Al10O13 and a large (18.8 × 10.7)A 2 nearly rectangular unit cell; an almost perfect match between substrate periodicity and the (1 × 2) oxide supercell is found. Nevertheless, microscopy reveals the presence of anti-phase domain boundaries. Measured Al 2p and O 1s core level shifts match calculated ones; their origin and the relative contributions of initial/final state effects are discussed. The ubiquity of the present oxide on different supports asks for the origin of its stability.
Published: 2020
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11. Decoupling Molybdenum Disulfide from Its Substrate by Cesium Intercalation

Author: Simone Lisi, Marco Bianchi, Olivier Geaymond, Valérie Guisset, Johann Coraux, Estelle Mazaleyrat, Ana Cristina Gómez Herrero, Van-Dung Nguyen, Gilles Renaud, Claude Chapelier, Roberto Sant, Matthieu Jamet, Philip Hofmann, Laurence Magaud, Philippe David, Yannick J. Dappe, Alain Marty, Systèmes hybrides de basse dimensionnalité (HYBRID), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), CRG et Grands Instruments (CRG), Epitaxie et couches minces (EpiCM), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Laboratoire de Transport Electronique Quantique et Supraconductivité (LaTEQS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Interdisciplinary Nanoscience Center (iNANO), Aarhus University [Aarhus], Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), CRG & Grands instruments (NEEL - CRG), Epitaxie et couches minces (NEEL- EpiCM), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Materials science, Intercalation (chemistry), Surface X-ray Diffraction, chemistry.chemical_element, FOS: Physical sciences, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, chemistry.chemical_compound, Molybdenum Disulfide, Transition metal, Intercalation, Lamellar structure, Physical and Theoretical Chemistry, Molybdenum disulfide, Condensed Matter - Materials Science, Substrate (chemistry), Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Crystallography, General Energy, chemistry, Scanning Tunneling Microscopy, Caesium, Density functional theory, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Decoupling (electronics)
Abstract: Intercalation of alkali atoms within the lamellar transition metal dichalcogenides is a possible route toward a new generation of batteries. It is also a way to induce structural phase transitions authorizing the realization of optical and electrical switches in this class of materials. The process of intercalation has been mostly studied in three-dimensional dichalcogenide films. Here, we address the case of a single-layer of molybdenum disulfide (MoS$_2$), deposited on a gold substrate, and intercalated with cesium (Cs) in ultra-clean conditions (ultrahigh vacuum). We show that intercalation decouples MoS$_2$ from its substrate. We reveal electron transfer from Cs to MoS$_2$, relative changes in the energy of the valence band maxima, and electronic disorder induced by structural disorder in the intercalated Cs layer. Besides, we find an abnormal lattice expansion of MoS$_2$, which we relate to immediate vicinity of Cs. Intercalation is thermally activated, and so is the reverse process of de-intercalation. Our work opens the route to a microscopic understanding of a process of relevance in several possible future technologies, and shows a way to manipulate the properties of two-dimensional dichalcogenides by "under-cover" functionalization., Comment: 6 figures
Published: 2020
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12. Massless Dirac Fermions in ZrTe2 Semimetal Grown on InAs(111) by van der Waals Epitaxy

Author: Hanako Okuno, Roberto Sant, Dimitra Tsoutsou, R. Alcotte, Sotirios Fragkos, Gilles Renaud, Thierry Baron, Polychronis Tsipas, Carlos Alvarez, Athanasios Dimoulas, National Center for Scienfic Research Demokritos, Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Nanostructures et Rayonnement Synchrotron (NRS ), Laboratoire des technologies de la microélectronique (LTM ), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Systèmes hybrides de basse dimensionnalité (HYBRID), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
Subjects: Materials science, General Physics and Astronomy, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, 7. Clean energy, law.invention, Condensed Matter::Materials Science, symbols.namesake, law, General Materials Science, Electronic band structure, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Valence (chemistry), Condensed matter physics, Graphene, Fermi level, General Engineering, 021001 nanoscience & nanotechnology, Semimetal, 0104 chemical sciences, Dirac fermion, symbols, van der Waals force, 0210 nano-technology, Molecular beam epitaxy
Abstract: Single and few layers of the two-dimensional (2D) semimetal ZrTe2 are grown by molecular beam epitaxy on InAs(111)/Si(111) substrates. Excellent rotational commensurability, van der Waals gap at the interface and moire pattern are observed indicating good registry between the ZrTe2 epilayer and the substrate through weak van der Waals forces. The electronic band structure imaged by angle resolved photoelectron spectroscopy shows that valence and conduction bands cross at the Fermi level exhibiting abrupt linear dispersions. The latter indicates massless Dirac Fermions which are maintained down to the 2D limit suggesting that single-layer ZrTe2 could be considered as the electronic analogue of graphene.
Published: 2018
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13. Development of a reactor for the in situ monitoring of 2D materials growth on liquid metal catalysts, using synchrotron x-ray scattering, Raman spectroscopy, and optical microscopy

Author: Irene M. N. Groot, F La Porta, Gilles Renaud, G. J. C. van Baarle, Mehdi Saedi, Maciej Jankowski, Anastasios C. Manikas, J M de Voogd, Costas Galiotis, A Sjardin, Oleg Konovalov, Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)
Subjects: 010302 applied physics, Liquid metal, Materials science, Atmospheric pressure, Graphene, chemistry.chemical_element, Chemical vapor deposition, 7. Clean energy, 01 natural sciences, Chemical reaction, Copper, 010305 fluids & plasmas, law.invention, Chemical state, symbols.namesake, chemistry, Chemical engineering, law, 0103 physical sciences, symbols, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Raman spectroscopy, Instrumentation
Abstract: Liquid metal catalysts (LMCats) (e.g., molten copper) can provide a new mass-production method for two-dimensional materials (2DMs) (e.g., graphene) with significantly higher quality and speed and lower energy and material consumption. To reach such technological excellence, the physicochemical properties of LMCats and the growth mechanisms of 2DMs on LMCats should be investigated. Here, we report the development of a chemical vapor deposition (CVD) reactor which allows the investigation of ongoing chemical reactions on the surface of a molten metal at elevated temperatures and under reactive conditions. The surface of the molten metal is monitored simultaneously using synchrotron x-ray scattering, Raman spectroscopy, and optical microscopy, thereby providing complementary information about the atomic structure and chemical state of the surface. To enable in situ characterization on a molten substrate at high temperatures (e.g., similar to 1370 K for copper), the optical and x-ray windows need to be protected from the evaporating LMCat, reaction products, and intense heat. This has been achieved by creating specific gas-flow patterns inside the reactor. The optimized design of the reactor has been achieved using multiphysics COMSOL simulations, which take into account the heat transfer, fluid dynamics, and transport of LMCat vapor inside the reactor. The setup has been successfully tested and is currently used to investigate the CVD growth of graphene on the surface of molten copper under pressures ranging from medium vacuum up to atmospheric pressure. Published under license by AIP Publishing.
Published: 2020
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14. In Situ X-ray Diffraction Study of GaN Nucleation on Transferred Graphene

Author: Patrick Le Fèvre, Tao Zhou, Jean-Christophe Harmand, Ludovic Largeau, Noelle Gogneau, Frank Glas, Ali Madouri, Olivier Geaymond, Maria Tchernycheva, Laurent Travers, Martina Morassi, Antonella Cavanna, Camille Barbier, and Gilles Renaud
Subjects: In situ, Diffraction, Materials science, 010405 organic chemistry, business.industry, Graphene, Nanowire, Nucleation, General Chemistry, Substrate (electronics), 010402 general chemistry, Condensed Matter Physics, 01 natural sciences, 0104 chemical sciences, law.invention, law, X-ray crystallography, Optoelectronics, General Materials Science, Crystallite, business
Abstract: We investigate by in situ X-ray diffraction the early stage of GaN nanowire growth on a single layer of polycrystalline graphene transferred onto a Si(100)/SiO2 carrier substrate. The experiment wa...
Published: 2020
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15. Topological band crossings in epitaxial strained SnTe

Author: Sigiava Aminalragia-Giamini, E. Golias, Carlos Alvarez, Gilles Renaud, Polychronis Tsipas, Jose Marquez-Velasco, Sotirios Fragkos, Roberto Sant, Hanako Okuno, Oliver Rader, Evangelia Xenogiannopoulou, Dimitra Tsoutsou, Athanasios Dimoulas, National Center for Scienfic Research Demokritos, Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratory of Atomistic Simulation (LSIM ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Nanostructures et Rayonnement Synchrotron (NRS ), Systèmes hybrides de basse dimensionnalité (HYBRID), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
Subjects: Materials science, Physics and Astronomy (miscellaneous), Dirac (software), Angle-resolved photoemission spectroscopy, 02 engineering and technology, Space (mathematics), Topology, 01 natural sciences, Condensed Matter::Materials Science, molecular beam epitaxy, transmission electron microscopy, 0103 physical sciences, General Materials Science, angle-resolved photoemission spectroscopy, 010306 general physics, Electronic band structure, density functional theory, topological materials, Valence (chemistry), 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik, 021001 nanoscience & nanotechnology, X-ray diffraction, Brillouin zone, density functional calculations, Density functional theory, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, Molecular beam epitaxy
Abstract: Epitaxial SnTe (111) is grown by molecular-beam epitaxy on $\mathrm{B}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{3}$ substrates. Structural evaluation indicates that SnTe deviates from cubic due to in-plane compressive strain, which induces significant changes in the electronic band structure. More specifically, a pair of gapless crossings between the two uppermost valence bands occurs in $k$ space along the out-of-plane \ensuremath{\Gamma}Z direction of the Brillouin zone, associated with a band inversion, thus defining topological three-dimensional Dirac nodes. Combined first-principles calculations and angle-resolved photoelectron spectroscopy reveal an overtilted Dirac cone indicating that the crossing is a topological type-III Dirac node at the borders between type-I and type-II Dirac nodes.
Published: 2019
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16. Elaboration of nanomagnet arrays: organization and magnetic properties of mass-selected FePt nanoparticles deposited on epitaxially grown graphene on Ir(111)

Author: P. Capiod, Philippe Ohresser, Clément Albin, Véronique Dupuis, O. Boisron, Alexandre Tamion, L. Bardotti, Florent Tournus, Gilles Renaud, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Nanostructures magnétiques (MAGNETIQUES), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon
Subjects: Materials science, Condensed matter physics, Annealing (metallurgy), Scattering, Magnetic circular dichroism, Graphene, Physics::Optics, General Physics and Astronomy, chemistry.chemical_element, Nanoparticle, Epitaxy, 01 natural sciences, Nanomagnet, law.invention, Condensed Matter::Materials Science, chemistry, law, 0103 physical sciences, Iridium, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics
Abstract: The moir\'e pattern created by the epitaxy of a graphene sheet on an iridium substrate can be used as a template for the growth of 2D atomic or cluster arrays. We observed for the first time a coherent organization of hard magnetic preformed FePt nanoparticles on the 2D lattice of graphene on Ir(111). Nanoparticles of 2 nm diameter have been mass selected in a gas phase and deposited with low energy on the hexagonal moir\'e pattern. Their morphology and organization have been investigated using grazing incidence small angle x-ray scattering, while their magnetic properties have been studied by x-ray magnetic circular dichroism, both pointing to a FePt cluster-graphene surface specific interaction. The spatial coherence of the nanoparticles is preserved upon annealing up to $700\text{ }\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ where the hard magnetic phase of FePt is obtained.
Published: 2019
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17. Room Temperature Commensurate Charge Density Wave in Epitaxial Strained TiTe 2 Multilayer Films

Author: Roberto Sant, Hanako Okuno, Sotirios Fragkos, Athanasios Dimoulas, Polychronis Tsipas, Alexei Bosak, Dimitra Tsoutsou, Gilles Renaud, Carlos Alvarez, National Center for Scienfic Research Demokritos, Systèmes hybrides de basse dimensionnalité (HYBRID), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire de Physique Théorique d'Orsay [Orsay] (LPT), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), European Synchrotron Radiation Facility (ESRF), Université Catholique de Louvain = Catholic University of Louvain (UCL), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Superconductivity, Phase transition, Reflection high-energy electron diffraction, Materials science, Condensed matter physics, Mechanical Engineering, Transition temperature, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, 0104 chemical sciences, Reciprocal lattice, Mechanics of Materials, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, Charge density wave, Molecular beam epitaxy
Abstract: International audience; Despite a large number of studies [2,3] over the years since the first discovery [7] and a couple of comprehensive reviews [8,9] the actual mechanism for PLD/CDW formation is still under debate. The most recent experimental [10-13] and theoretical [14] works focus on the large area growth of the CDW phase [13] the thickness dependence , and the possible unconventional behavior in the ultimate 2D limit of a single layer TiSe 2. [10-12,14] On the other hand, the other Ti dichalcogenides namely TiS 2 and TiTe 2 did not show any clear evidence until very recently when a CDW state was reported only for 1 monolayer (ML)-thin TiTe 2 at temperatures lower than 92 K. [15] It is surprising that the CDW in TiTe 2 was found to be totally suppressed for films thicker than 1 ML, [15] unlike the case of other TMDs where 1 ML and bulk-like films both make the transition to a CDW at nearly the same temperature. The interest about TiTe 2 is continuously increasing in view of theoretical predictions [16] and more recent experimental evidence [17] about pressure induced topological phase transitions in TiTe 2. The possibility to also manipulate superconduc-tivity by external pressure as predicted [18] and more recently evidenced [19] in bulk TiTe 2 creates the prospect to explore the emergence of topological superconductivity in this material. In the latter work [19] it has been shown that under nonhydro-static pressure, a CDW-like state with estimated transition temperature above room temperature (RT) appears in bulk TiTe 2 at around 0.5-1.8 GPa. These results call for a re-examination of the possibility to obtain a CDW in multilayer TiTe 2 and indeed at RT with good potential for real world applications utilizing the properties of the CDW state. These applications include a voltage-controlled oscillator device operating at room temperature , [20] fast electronic resistance switching for nonvolatile memories, [21,22] and field-effect transistor devices potentially suitable for implementation of non-Boolean logic. [23] In this paper it is shown that multilayer films (50 ML ≈ 32 nm), as well as single layer TiTe 2 epitaxially grown on InAs(111)/ Si(111) substrates by molecular beam epitaxy exhibit, in ambient pressure conditions, a CDW distortion at room temperature which is sustained up to higher temperatures, at least 400 °C, as evidenced by reflection high energy electron diffrac-tion (RHEED) (Figure S1, Supporting Information). The results are explained in terms of anisotropic strain imposed by the substrate. The group IVB 2D transition metal dichalcogenides are considered to be stable in the high symmetry trigonal octahedral structure due to the lack of unpaired d-electrons on the metal site. It is found that multilayer epitaxial TiTe 2 is an exception adopting a commensurate 2 × 2 × 2 charge density wave (CDW) structure at room temperature with an ABA type of stacking as evidenced by direct lattice imaging and reciprocal space mapping. The CDW is stabilized by highly anisotropic strain imposed by the substrate with an out-off-plane compression which reduces the interlayer van der Waals gap increasing the coupling between TiTe 2 layers.
Published: 2019
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18. Al-rich Fe0.85Al0.15(1 0 0), (1 1 0) and (1 1 1) surface structures

Author: Gilles Renaud, Jacques Jupille, Zongbei Dai, Patrizia Borghetti, Rémi Lazzari, Pascal David, Natalia Alyabyeva, Stéphane Chenot, Gregory Cabailh, and Alexey Koltsov
Subjects: Diffraction, Materials science, Alloy, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, Surfaces and Interfaces, General Chemistry, engineering.material, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, 0104 chemical sciences, Surfaces, Coatings and Films, Faceting, Crystallography, Electron diffraction, chemistry, Aluminium, Microscopy, engineering, 0210 nano-technology, Superstructure (condensed matter), Vicinal
Abstract: Based on previous photoemission findings, the influence of newly observed aluminum surface segregation at the low (110), (100) and (111) index surfaces of the A 2 body-centered Fe 0.85 Al 0.15 random alloy is explored. Scanning Tun-neling Microscopy, Low-Energy Electron Diffraction and Grazing-Incidence X-Ray Diffraction are combined to explore surface structures and topogra-phies. The formation of a surface composition close to the B 2 Fe 0.5 Al 0.5 occurs with the appearance of (i) a long-range pseudo-hexagonal incommen-surate superstructure with a periodicity of ∼ 18A on the (110) surface, (ii) a (1 × 1) termination on the (100) surface and (iii) a intense vicinal faceting of the (111) surface in the form of triangular pits.
Published: 2020
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19. Beyond van der Waals Interaction: The Case of MoSe$_2$ Epitaxially Grown on Few-Layer Graphene

Author: Minh Tuan Dau, Maxime Gay, Daniela Di Felice, Céline Vergnaud, Alain Marty, Cyrille Beigné, Gilles Renaud, Olivier Renault, Pierre Mallet, Toai Le Quang, Jean-Yves Veuillen, Loïc Huder, Vincent T. Renard, Claude Chapelier, Giovanni Zamborlini, Matteo Jugovac, Vitaliy Feyer, Yannick J. Dappe, Pascal Pochet, Matthieu Jamet, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Nano-Electronique Quantique et Spectroscopie (QuNES), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire de Transport Electronique Quantique et Supraconductivité (LaTEQS), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association, Laboratory of Atomistic Simulation (LSIM ), ANR-14-CE26-0017,MoS2ValleyControl,Propriétés optiques et de transport dans des mono-couches de MoS2 et discpositifs associés(2014), ANR-11-EQPX-0010,CRGF,Lignes synchrotron françaises à l'ESRF(2011), ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), European Project: 604391,EC:FP7:ICT,FP7-ICT-2013-FET-F,GRAPHENE(2013), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Nano-Electronique Quantique et Spectroscopie (NEEL - QuNES)
Subjects: Materials science, heterojunction, Band gap, General Physics and Astronomy, 02 engineering and technology, MoSe2, Epitaxy, 01 natural sciences, Electron spectroscopy, law.invention, symbols.namesake, law, 0103 physical sciences, Physics::Atomic and Molecular Clusters, band-gap opening, General Materials Science, 010306 general physics, Electronic band structure, [PHYS]Physics [physics], Condensed matter physics, Graphene, General Engineering, charge transfer, Heterojunction, commensurability, 021001 nanoscience & nanotechnology, few-layer graphene, van der Waals interaction, symbols, Density functional theory, van der Waals force, 0210 nano-technology
Abstract: International audience; Van der Waals heterojunctions composed of graphene and transition metal dichalcogenides have gain much attention because of the possibility to control and tailor band structure, promising applications in two-dimensional optoelectronics and electronics. In this report, we characterized the van der Waals heterojunction MoSe$_2$/few-layer graphene with a high-quality interface using cutting-edge surface techniques scaling from atomic to microscopic range. These surface analyses gave us a complete picture of the atomic structure and electronic properties of the heterojunction. In particular, we found two important results: the commensurability between the MoSe$_2$ and few-layer graphene lattices and a band-gap opening in the few-layer graphene. The band gap is as large as 250 meV, and we ascribed it to an interface charge transfer that results in an electronic depletion in the few-layer graphene. This conclusion is well supported by electron spectroscopy data and density functional theory calculations. The commensurability between the MoSe$_2$ and graphene lattices as well as the band-gap opening clearly show that the interlayer interaction goes beyond the simple van der Waals interaction. Hence, stacking two-dimensional materials in van der Waals heterojunctions enables us to tailor the atomic and electronic properties of individual layers. It also permits the introduction of a band gap in few-layer graphene by interface charge transfer.
Published: 2018
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20. Beyond van der Waals Interaction: The Case of MoSe

Author: Minh Tuan, Dau, Maxime, Gay, Daniela, Di Felice, Céline, Vergnaud, Alain, Marty, Cyrille, Beigné, Gilles, Renaud, Olivier, Renault, Pierre, Mallet, Toai, Le Quang, Jean-Yves, Veuillen, Loïc, Huder, Vincent T, Renard, Claude, Chapelier, Giovanni, Zamborlini, Matteo, Jugovac, Vitaliy, Feyer, Yannick J, Dappe, Pascal, Pochet, and Matthieu, Jamet
Abstract: Van der Waals heterojunctions composed of graphene and transition metal dichalcogenides have gain much attention because of the possibility to control and tailor band structure, promising applications in two-dimensional optoelectronics and electronics. In this report, we characterized the van der Waals heterojunction MoSe
Published: 2018

21. Massless Dirac Fermions in ZrTe

Author: Polychronis, Tsipas, Dimitra, Tsoutsou, Sotirios, Fragkos, Roberto, Sant, Carlos, Alvarez, Hanako, Okuno, Gilles, Renaud, Reynald, Alcotte, Thierry, Baron, and Athanasios, Dimoulas
Abstract: Single and few layers of the two-dimensional (2D) semimetal ZrTe
Published: 2018

22. Integration techniques for surface x-ray diffraction data obtained with a two-dimensional detector

Author: Tao Zhou, Gilles Renaud, Willem G. Onderwaater, Elias Vlieg, Jakub Drnec, Roberto Felici, Stelian Pintea, European Synchrotron Radiation Facility (ESRF), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Universiteit Leiden, Radboud University [Nijmegen], Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Universiteit Leiden [Leiden], and Radboud university [Nijmegen]
Subjects: Surface (mathematics), Physics, Diffraction, Pixel, business.industry, Detector, Solid State Chemistry, Space (mathematics), General Biochemistry, Genetics and Molecular Biology, Reciprocal lattice, Optics, X-ray crystallography, [CHIM.CRIS]Chemical Sciences/Cristallography, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], business, Intensity (heat transfer)
Abstract: International audience; Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr. For further information see http://journals.iucr.org/services/authorrights.html Many research topics in condensed matter research, materials science and the life sciences make use of crystallographic methods to study crystalline and non-crystalline matter with neutrons, X-rays and electrons. Articles published in the Journal of Applied Crystallography focus on these methods and their use in identifying structural and diffusion-controlled phase transformations, structure-property relationships, structural changes of defects, interfaces and surfaces, etc. Developments of instrumentation and crystallographic apparatus, theory and interpretation, numerical analysis and other related subjects are also covered. The journal is the primary place where crystallographic computer program information is published. This article proposes two integration methods to determine the structure factors along a surface diffraction rod measured with a two-dimensional detector. The first method applies the classic way of calculating integrated intensities in angular space. This is adapted to work efficiently with two-dimensional data. The second method is based on integration in reciprocal space. An intensity map is created by converting the detected intensity pixel by pixel to the reciprocal space. The integration is then performed directly on this map. A theoretical framework, as well as a comparison between the two integration methods, is provided.
Published: 2014
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23. Propriétés structurales de surfaces, interfaces et nanostructures, étudiées à l’aide des rayons X

Author: Gilles Renaud
Subjects: General Medicine
Abstract: La diffusion/diffraction et l’absorption des rayons X issus d’une source synchrotron sont des techniques tres puissantes d’etude de la structure, de la morphologie et de la composition de surfaces, d’interfaces et de nano-objets, en particulier in situ , durant leur elaboration, ou in operando .Nous les illustrons par l’exemple de la croissance de germanium sur des surfaces (001) de silicium monocristallin, ou apparaissent successivement une couche bidimensionnelle contrainte presentant un arrangement complexe des atomes de surface, puis differentes nanostructures facettees qui relaxent progressivement leur parametre de maille via une interdiffusion avec le substrat.
Published: 2013
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24. Temperature evolution of defects and atomic ordering in Si 1− x Ge x islands on Si(001)

Author: Marie-Ingrid Richard, Tobias U. Schülli, Gilles Renaud, T. H. Metzger, Angelo Malachias, Tsvetelina Merdzhanova, Markus Stoffel, Oliver G. Schmidt, Institut des Matériaux, de Microélectronique et des Nanosciences de Provence (IM2NP), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Universidade Federal de Minas Gerais [Belo Horizonte] (UFMG), Laboratory of Dendrogeomorphology, Department of Geosciences, Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), European Synchrotron Radiation Facility (ESRF), Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
Subjects: Diffraction, Materials science, Condensed matter physics, Relaxation (NMR), General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, Isotropic etching, Crystallography, Reflection (mathematics), Etching, 0103 physical sciences, X-ray crystallography, ddc:530, Self-assembly, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract: International audience; The observation of atomic ordering and signatures of defects in self-assembled Ge islands using x-ray diffraction techniques have been previously treated as unrelated subjects. However, mutual understanding can be achieved when both subjects are studied in a common frame. Here, we report on measurements and analysis of both defects and atomic ordering in Si1-xGex islands epitaxially grown on Si(001) substrates as a function of growth temperature. By using x-ray diffraction and mapping around a bulk forbidden reflection, defect sizes, and in-plane spacing between nearby dislocations are extracted and related to the composition of the islands. The results fit well with an independent determination using selective wet chemical etching and atomic force microscopy measurements. Moreover, the temperature dependence of the ordered domain size is discussed. Although both atomic ordering and defect formation take place independently in the system, it is found that the relaxation provided by the onset of defects does not affect the formation of ordered domains, recently pointed out to be stabilized by strain and surface equilibrium on islands facets. (C) 2016 AIP Publishing LLC.
Published: 2016
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25. CO-Induced Scavenging of Supported Pt Nanoclusters: A GISAXS Study

Author: Edmar A. Soares, Nihed Chaâbane, Jacques Jupille, Rémi Lazzari, Gilles Renaud, Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences et Techniques Nucléaires (INSTN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Oxydes en basses dimensions (INSP-E9), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Annealing (metallurgy), Nanotechnology, 02 engineering and technology, 010402 general chemistry, Platinum nanoparticles, Photochemistry, 01 natural sciences, Nanoclusters, chemistry.chemical_compound, Physical and Theoretical Chemistry, Scavenging, ComputingMilieux_MISCELLANEOUS, Bond strength, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, General Energy, chemistry, Agglomerate, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Grazing-incidence small-angle scattering, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, Carbon monoxide
Abstract: Supported platinum nanoparticles in the presence of carbon monoxide in the 10–6–103 Pa CO pressure range were studied by grazing incidence small-angle X-ray scattering. Disruption and aggregation of platinum nanoparticles upon CO exposure are shown to occur in parallel. Particles smaller than a critical size of 1 nm undergo scavenging after disruption in the form of carbonyls at CO pressure as low as 10–1 Pa. Mobile carbonyls then agglomerate to larger clusters. Upon annealing, a CO-driven diffusion and agglomeration of clusters of size ranging between the critical size and 2 nm is observed. These phenomena are discussed in relation to the CO–metal, metal–metal, and metal–substrate relative bond strengths. Similar mechanisms are suggested to hold for other supported metal catalysts.
Published: 2012
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26. Growth and dewetting of gold on Si(111) investigated in situ by grazing incidence small angle x-ray scattering

Author: Gilles Renaud, R. Daudin, C. Revenant, and Giovanni Davi
Subjects: Materials science, Annealing (metallurgy), Nanowire, Nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Nanoclusters, Contact angle, Chemical physics, Monolayer, Dewetting, Wetting layer, Eutectic system
Abstract: The most accessible way to grow semiconductor nanowires remains so far the use of gold nanoclusters on a (1 1 1) semiconductor surface, for instance Si(1 1 1). Precise knowledge of the morphology of gold nanoparticles obtained by growth or dewetting on Si(1 1 1) is essential to better control the growth of nanowires. Both formation routes were investigated in situ by grazing incidence small-angle x-ray scattering. During the growth at 300 °C, Au atoms first nucleate on the wetting layer and give rise to islands having the shape of truncated spheres with an average contact angle of 38° for deposits of 1.4 and 2 monolayers. Dewetting is obtained by annealing of a 2 monolayer room temperature deposit, leading to the formation of particles. The average contact angle increases from 53° to 73° from 270 °C to 360 °C. Moreover, an analysis of the island height suggests that an AuSi alloy with a thickness of approximately 1.5 nm could be present at the top of the monocrystalline islands in the solid state before the eutectic temperature. The liquid–solid interface tension of the AuSi alloy droplet (1.0 J m−2) and the work of adhesion (1.1 J m−2) are deduced at the eutectic temperature.
Published: 2012
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27. A Combined In Situ Grazing Incidence Small Angle X-Ray Scattering and Grazing Incidence X-Ray Diffraction Study of the Growth of Ge Islands on Pit-Patterned Si(001) Substrates

Author: Gilles Renaud, G. Bauer, Marie-Ingrid Richard, Zhong Zz, and T. U. Schülli
Subjects: Grazing incidence diffraction, Materials science, Small-angle X-ray scattering, Biomedical Engineering, Bioengineering, General Chemistry, Substrate (electronics), Condensed Matter Physics, Crystallography, Wavelength, X-ray crystallography, Grazing-incidence small-angle scattering, General Materials Science, Small-angle scattering, Intensity (heat transfer)
Abstract: The growth of Ge islands on a pit-patterned Si(001) template is investigated in situ, combining grazing incidence diffraction, multiple wavelength anomalous diffraction, and small angle scattering. This allows monitoring in situ the detailed structural and morphological evolutions of the pits, of the wetting-layer and of the nucleated islands on the pit-patterned Si(001) substrate. It is shown that after Si regrowth, the Si substrate displays {107} and {1 1 11} facets. During the very first stages of Ge growth, the preliminary facets of the Si substrate are energetically unfavourable, and the pit facets break up into a rather complex pattern of {10n} and {11m} facets with n > 7 and m > 11. At 5 and 6 ML, intensity rods from {105} and {113}-type facets appear in the GISAXS images revealing the formation of pyramids and domes, respectively. The degree of ordering, the shape, strain and composition of the islands are characterized during the growth process to provide a detailed evolution of their structure and morphology.
Published: 2011
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28. Direct Observation at Room Temperature of the Orthorhombic Weyl Semimetal Phase in Thin Epitaxial MoTe2

Author: Athanasios Dimoulas, Polychronis Tsipas, Dimitra Tsoutsou, Sotirios Fragkos, Carlos Alvarez, Roberto Sant, Hanako Okuno, Gilles Renaud, National Center for Scienfic Research Demokritos, Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Nanostructures et Rayonnement Synchrotron (NRS ), National Center for Scientific Research 'Demokritos' (NCSR), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Systèmes hybrides de basse dimensionnalité (HYBRID)
Subjects: Materials science, Condensed matter physics, Stacking, Weyl semimetal, Fermi energy, 02 engineering and technology, Triclinic crystal system, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Antibonding molecular orbital, 01 natural sciences, Electronic, Optical and Magnetic Materials, Biomaterials, Condensed Matter::Materials Science, Condensed Matter::Superconductivity, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, Electrochemistry, Condensed Matter::Strongly Correlated Electrons, Orthorhombic crystal system, 010306 general physics, 0210 nano-technology, Molecular beam epitaxy, Monoclinic crystal system
Abstract: International audience; The direct observation at room temperature (RT) of the noncentrosym-metric orthorhombic topological Weyl semimetal phase in epitaxial thin films of MoTe 2 grown on InAs(111)/Si(111) substrates by molecular beam epitaxy (MBE) is reported. The orthorhombic phase is typically found at lower temperatures but its observation at RT in this work is attributed to the enlarged lattice parameters, influenced by the substrate, which stabilize an interlayer antibonding state compatible with the orthorhombic stacking. First-principles calculations predict eight type II Weyl nodes which are located below (but near) the Fermi energy making them accessible to charge transport and creating the prospect for practical applications exploiting the nontrivial topological properties. The orthorhombic phase coexists with an unconventional triclinic layer stacking which is different than the monoclinic or orthorhombic structures but it is centrosymmetric and topologically trivial.
Published: 2018
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29. (Invited) Large Area Synthesis of 2D Metal Dichalcogenides By Van Der Waals Molecular Beam Epitaxy

Author: Athanasios Dimoulas, Dimitra Tsoutsou, Polichronis Tsipas, Sotiris Fragkos, Roberto Sant, Carlos Alvarez, Hanako Okuno, and Gilles Renaud
Abstract: A large number of 2D Transition Metal Dichalcogenide (TMD) materials on micron-sized flakes exfoliated from bulk have been studied extensively showing exciting new physical properties and good prospects to impact a wide range of applications [1]. On the other hand, large area growth on suitable substrates is urgently needed in order to make the transition from lab-based research to real world applications. Molecular beam epitaxy (MBE) is traditionally used to achieve van der Waals epitaxy as first conceptualized by Koma and co-workers[2]. The epitaxial growth of single or few layer 2D TMDs is very challenging because it depends critically on the substrate and surface preparation methodology. Although Si as one of the most technologically important substrates is preferred for TMD growth, the film quality is not adequate. Engineered substrates such as epi-AlN(0001)/Si and epi-InAs(111)/Si available in large wafer sizes (200 and 300 mm) could be good candidates in the effort to improve the thin film quality. In this work, we will first review our work on MoSe2 [3], HfSe2 [4] WSe2[5], SnSe2[5] and HfTe2 [6] and their van der Waals heterostructures [5,7] grown by MBE on AlN/Si focusing on the microstructure, thin film morphology and homogeneity. Then we will show more recent results on metallic or semimetallic telluride TMDs (MoTe2, TiTe2, ZrTe2, HfTe2) grown on InAs/Si substrates with much improved epitaxial quality. Using synchrotron XRD, high resolution STEM and in-situ STM, excellent rotational commensurability, quasi van der Waals gap at the interface and Moire pattern are observed indicating good registry between the 2D TMD epilayer and the substrate through weak van der Waals forces. We will show that MBE grown 1ML MoTe2 on InAs(111) adopts the metastable distorted 1T’ crystal structure which is metallic and predicted to be a 2D tolological insulator (or Quantum Spin Hall state). Using in-situ ARPES complemented by DFT calculations we show that the valence and conduction bands of few layer HfTe2 [6] and ZrTe2 cross at the Fermi level exhibiting abrupt linear dispersions at the zone center. The latter indicates massles Dirac fermions which are maintained down to the 2D limit suggesting that single layers of epitaxial HfTe2 and ZrTe2 could be considered as the electronic analogue of graphene. Finally, we show that in 1 ML TiTe2 it is possible to substitute the top Te row by Se to form the ordered Janus ternary 2D material Te-Ti-Se similar to S-Mo-Se material recently reported [8,9]. These materials are predicted to have exiting new physical properties and are expected to open a new field in the wide area of 2D materials and devices. Acknowledgements: This work is financially supported by the LANEF Chair of Excellence program of U. Grenoble Alpes and CEA (A.D.), the Greek State Scholarships Foundation (IKY) Program for the strengthening of postdoctoral research (P.T.), The FLAG-ERA project MELoDICA (A.D.) and the French state funds ANR-10-LABX-51-01 (Labex LANEF du Programme d'Investissements d'Avenir) and Equipex ANR-11-EQPX-0010 (G.R.) References: [1] W. Choi, et al., Materials Today, 20(3), 116-130, (2017); [2] A. Koma, J. Cryst. Growth, 201/202, 236-241 (1999); [3] E. Xenogiannopoulou, et al., Nanoscale, 7, 7896-7905, (2015); [4] K. E. Aretouli, et al., Appl. Phys. Lett. 106, 143105 (2015) ; [5] K. E. Aretouli et al., ACS Appl. Mater. Interfaces 8, 23222-23229 (2016); [6] S. A. Giamini et al., 2D Mater. 4, 015001 (2017); [7] D. Tsoutsou, et al., ACS Appl. Mater. Interfaces 8, 1836-1841 (2016).
Published: 2018
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30. Coalescence of domes and superdomes at a low growth rate or during annealing: Towards the formation of flat-top superdomes

Author: G. Chen, G. Bauer, Gilles Renaud, Marie-Ingrid Richard, and T. U. Schülli
Subjects: Materials science, Silicon, Annealing (metallurgy), Nucleation, chemistry.chemical_element, Surfaces and Interfaces, Atmospheric temperature range, Condensed Matter Physics, Epitaxy, Surfaces, Coatings and Films, Faceting, Crystallography, chemistry, Chemical physics, Materials Chemistry, Growth rate, Molecular beam epitaxy
Abstract: We investigate the morphology of islands obtained by epitaxial growth of Ge on Si(0 0 1). During a low growth rate or during annealing and depending of the quench method, we observe the formation of a new type of superdomes, which exhibit additional {15 3 23} facets, an increase of their {0 0 1} and {1 0 5} facet area on their top and a smaller aspect ratio compared to known superdomes. This flat-top superdome shape results from the complex evolution of domes and superdomes: coalescence, intermixing and ripening. Dome or superdome coalescence which results in the newly observed shape appears as a dominant pathway towards dislocation nucleation for the investigated temperature range.
Published: 2008
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31. Atomic structure of Pt nanoclusters supported by graphene/Ir(111) and reversible transformation under CO exposure

Author: Gilles Renaud, Sven Runte, Thomas Michely, Johann Coraux, Carsten Busse, Andreas Stierle, Dirk Franz, Timm Gerber, Uta Hejral, Peter J. Feibelman, Nils Blanc, Deutsches Elektronen-Synchrotron [Hamburg] (DESY), CRG & Grands instruments (NEEL - CRG), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), II. Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, DESY, NanoLab, Notkestr 85, D-22607 Hamburg, Germany, CRG et Grands Instruments (CRG ), Systèmes hybrides de basse dimensionnalité (HYBRID), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Universität zu Köln
Subjects: Materials science, Graphene, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, Nanoclusters, Crystallography, Lattice constant, chemistry, law, 0103 physical sciences, Monolayer, Cluster (physics), Grazing-incidence small-angle scattering, ddc:530, Density functional theory, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Atomic physics, 010306 general physics, 0210 nano-technology, Platinum, ComputingMilieux_MISCELLANEOUS
Abstract: We have investigated the atomic structure of graphene/Ir(111) supported platinum clusters with on average fewer than 40 atoms by means of surface x-ray diffraction (SXRD), grazing incidence small angle x-ray scattering (GISAXS), and normal incidence x-ray standing waves (NIXSW) measurements, in comparison with density functional theory calculations (DFT). GISAXS revealed that the clusters with 1.3 nm diameter form a regular array with domain sizes of 90 nm. SXRD shows that the 1--2 monolayer high, (111) oriented Pt nanoparticles grow epitaxially on the graphene support. From the combined analysis of the SXRD and NIXSW data, a three-dimensional (3D) structural model of the clusters and the graphene support can be deduced which is in line with the DFT results. For the clusters grown in ultrahigh vacuum the lattice parameter is reduced by $(4.6\ifmmode\pm\else\textpm\fi{}0.1)%$ compared to bulk platinum. The graphene layer undergoes a strong Pt adsorption induced buckling, caused by a rehybridization of the carbon atoms below the cluster. In situ observation of the Pt clusters in CO and ${\mathrm{O}}_{2}$ environments revealed a reversible change of the clusters' strain state while successively dosing CO at room temperature and ${\mathrm{O}}_{2}$ at 575 K, pointing to a CO oxidation activity of the Pt clusters.
Published: 2016
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32. Nano-structuration of CoO film by misfit dislocations

Author: Edmar A. Soares, Piero Torelli, Xiangxin Guo, Gilles Renaud, Sergio Valeri, and Paola Luches
Subjects: Grazing incidence X-ray diffraction, Grazing incidence diffraction, Low-energy electron diffraction, Photoemission spectroscopy, AG(100), Surfaces and Interfaces, Substrate (electronics), Condensed Matter Physics, Mosaicity, Heteroepitaxy, Strain release, Surfaces, Coatings and Films, Crystallography, Lattice constant, Metal–oxide interfaces, Cobalt oxide, Low energy electron diffraction, X-ray photoelectron spectroscopy, FE(001), Materials Chemistry, GROWTH, MGO FILMS, Dislocation
Abstract: We have studied the nano-patterning of CoO film induced by misfit dislocation network at the interface with the Ag(001) substrate. Grazing incidence diffraction (GIXD), X-ray photoemission spectroscopy (XPS) and low energy electron diffraction (LEED) have been used to characterize chemistry and structure of the CoO layers. The XPS spectrum of the Co 2p core level permitted to establish the stoichiometric growth of CoO. The structure of the CoO film together with the absorption sites of cobalt and oxygen atoms was determined, thanks to GIXD measurements. Moreover we have followed the evolution of the in-plane lattice constant of the CoO as a function of the film thickness. It turns out that the CoO film growth starts with the same in-plane lattice constant of the Ag(001) substrate up to 3-4 ML; afterwards the in-plane parameter of CoO steadily increases before reaching a stable value of 2.98 angstrom at 23 ML. During the relaxation process, at about 8 ML of film thickness, we observe the formation of a buried misfit dislocation network. These dislocations, that have a period of 9.2 nm for a film thickness of 23 ML, induce mosaicity in the CoO film which then appears as a regular distribution of tilted domains. (C) 2006 Elsevier B.V. All rights reserved.
Published: 2007
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33. Bentham's Theory Of Law and Public Opinion

Author: Gilles Renaud
Subjects: Legal positivism, business.industry, Law, Philosophy, Jeremy bentham, Public opinion, business
Published: 2015
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34. Moiré induced organization of size-selected Pt clusters soft landed on epitaxial graphene

Author: Fabien Jean, Gilles Renaud, Tao Zhou, Clément Albin, L. Bardotti, Florent Tournus, Sébastien Linas, Groupe NanoSciences (CEMES-GNS), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Systèmes hybrides de basse dimensionnalité (HYBRID), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)
Subjects: Multidisciplinary, Materials science, Annealing (metallurgy), Scattering, Graphene, Nanoparticle, 02 engineering and technology, 021001 nanoscience & nanotechnology, Epitaxy, Bioinformatics, 01 natural sciences, Molecular physics, Article, Nanoclusters, law.invention, Colloidal gold, law, 0103 physical sciences, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Scanning tunneling microscope, 010306 general physics, 0210 nano-technology
Abstract: Two-dimensional hexagonal arrays of Pt nanoparticles (1.5 nm diameter) have been obtained by deposition of preformed and size selected Pt nanoparticles on graphene. This original self-organization is induced, at room temperature, by the 2D periodic undulation (the moiré pattern) of graphene epitaxially grown on the Ir(111) surface. By means of complementary techniques (scanning tunneling microscopy, grazing incidence X ray scattering), the Pt clusters shapes and organization are characterized and the structural evolution during annealing is investigated. The soft-landed clusters remain quasi-spherical and a large proportion appears to be pinned on specific moiré sites. The quantitative determination of the proportion of organized clusters reveals that the obtained hexagonal array of the almost spherical nanoparticles is stable up to 650 K, which is an indication of a strong cluster-surface interaction.
Published: 2015
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35. Topography of the graphene/Ir(111) moiré studied by surface x-ray diffraction

Author: Johann Coraux, Fabien Jean, Roberto Felici, Nils Blanc, Tao Zhou, Gilles Renaud, Systèmes hybrides de basse dimensionnalité (HYBRID), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Institut Nanosciences et Cryogénie (INAC), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CRG et Grands Instruments (CRG), European Synchrotron Radiation Facility (ESRF), ANR-10-BLAN-1019,NMGEM,Nanomagnétisme sur Graphène Epitaxié sur Métaux(2010), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and CRG & Grands instruments (NEEL - CRG)
Subjects: Diffraction, Materials science, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Surface finish, 01 natural sciences, law.invention, Optics, law, Phase (matter), 0103 physical sciences, Iridium, Specular reflection, 010306 general physics, Condensed Matter - Materials Science, Graphene, business.industry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Amplitude, chemistry, X-ray crystallography, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, business
Abstract: International audience; The structure of a graphene monolayer on Ir(111) has been investigated {\it in situ} in the growth chamber by surface x-ray diffraction including the specular rod, which allows disentangling the effect of the sample roughness from that of the nanorippling of graphene and iridium along the moiré-like pattern between graphene and Ir(111). Accordingly we are able to provide precise estimates of the undulation associated with this nanorippling, which is small in this weakly interacting graphene/metal system and thus proved difficult to assess in the past. The nanoripplings of graphene and iridium are found in phase, i.e. the in-plane position of their height maxima coincide, but the amplitude of the height modulation is much larger for graphene ($0.379 \pm 0.044$ \AA) than, {\it e.g.}, for the topmost Ir layer ($0.017 \pm 0.002$ \AA). The average graphene-Ir distance is found to be $3.38 \pm 0.04$ \AA.
Published: 2015
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36. The In situ growth of Nanostructures on Surfaces (INS) endstation of the ESRF BM32 beamline: a combined UHV–CVD and MBE reactor for in situ X-ray scattering investigations of growing nanoparticles and semiconductor nanowires

Author: Tao Zhou, Gilles Renaud, O. Geaymond, O. Ulrich, Nils Blanc, V. Cantelli, Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), CRG et Grands Instruments (CRG), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and CRG & Grands instruments (NEEL - CRG)
Subjects: Nuclear and High Energy Physics, Auger electron spectroscopy, Radiation, Reflection high-energy electron diffraction, Materials science, Scattering, GIXRD, Nanowire, in situ, Nanotechnology, UHV–CVD, UHV-CVD, GIRD, In situ, Electron diffraction, Beamline, nanowires, IF-BM32, Grazing-incidence small-angle scattering, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Instrumentation, GISAXS, Molecular beam epitaxy
Abstract: International audience; The In situ growth of Nanostructures on Surfaces (INS) endstation of the ESRF BM32 beamline: a combined UHV-CVD and MBE reactor for in situ X-ray scattering investigations of growing nanoparticles and semiconductor nanowires This paper presents the upgraded 'In situ growth of Nanoscructures on Surfaces' (INS) endstation of the InterFace beamline IF-BM32 at the European Synchrotron Radiation Facility (ESRF). This instrument, originally designed to investigate the structure of clean surfaces/interfaces/thin-films by surface X-ray diffraction, has been further developed to investigate the formation and evolution of nanostructures by combining small-and wide-angle X-ray scattering methodologies, i.e. grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence X-ray diffraction (GIXD). It consists of a UHV chamber mounted on a z-axis type goniometer, equipped with residual gas analysis, reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES) to complete the X-ray scattering investigations. The chamber has been developed so as up to eight sources of molecular beam epitaxy (MBE) can be simultaneously mounted to elaborate the nanostructures. A chemical vapor deposition (CVD) setup has been added to expand the range of growing possibilities, in particular to investigate in situ the growth of semiconductor nanowires. This setup is presented in some detail, as well as the first in situ X-ray scattering measurements during the growth of silicon nanowires.
Published: 2015
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37. Formation, stability, and atomic structure of theSi(111)−(6×6)Ausurface reconstruction: A quantitative study using synchrotron radiation

Author: Alain Pasturel, R. Daudin, T. Nogaret, Gilles Renaud, T. U. Schülli, and Adrien Vaysset
Subjects: Diffraction, Materials science, Silicon, Annealing (metallurgy), chemistry.chemical_element, Nanotechnology, Condensed Matter Physics, Molecular physics, Electronic, Optical and Magnetic Materials, chemistry, Ab initio quantum chemistry methods, X-ray crystallography, Dewetting, Surface reconstruction, Eutectic system
Abstract: The conditions of formation of the Au-induced Si-(6×6) reconstruction, its stability, as well as its atomic structure are studied experimentally using grazing incidence x-ray diffraction techniques. This reconstruction is found to form at 680 K when cooling down eutectic droplets previously obtained by the dewetting of thin gold films deposited at room temperature on a Si(111) substrate. The quality of the reconstruction is found to depend on the annealing temperature. The formation of the (6×6) reconstruction at low temperature after it has been destroyed by ion bombardment, together with the recovery of the Si surface, give evidence of its high stability and highlight the surfactant properties of gold atoms. The determination of the Si(111)-(6 × 6)Au atomic structure is performed using quantitative surface x-ray diffraction with an existing complex model proposed in the literature as a starting structure. The resulting gold structure is found to be 1 ML thick and consists in two domains related by a mirror. They are composed of trimer and pentagonal units with special sites presenting a partial occupancy of 0.5. Our experimental data set does not provide enough accuracy to determine the positions of the Si atoms of the substrate, but ab initio calculations tend to confirm that they are only slightly displaced from the bulk position.
Published: 2015
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38. Growth mode, strain state and shape of Ge islands during their growth at different temperatures: a combined in situ GISAXS and GIXD study

Author: G. Bauer, Gilles Renaud, E. Wintersberger, Marie-Ingrid Richard, and T. U. Schülli
Subjects: Silicon, Chemistry, Small-angle X-ray scattering, technology, industry, and agriculture, Metals and Alloys, Nucleation, chemistry.chemical_element, Crystal growth, Surfaces and Interfaces, Substrate (electronics), Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Crystallography, Chemical physics, Materials Chemistry, Grazing-incidence small-angle scattering, Deformation (engineering), Small-angle scattering
Abstract: The growth mode, strain state and shape of Ge islands were analyzed in situ, during their growth on Si(001), by combining Grazing Incidence Small Angle X-ray Scattering (GISAXS) and Grazing Incidence X-ray Diffraction (GIXD) measurements. GISAXS measurements provide the detailed evolution of the shape of the grown quantum dots (QDs). GIXD allows the monitoring of the island nucleation and the strain state of the QDs. The shape, size, strain and interdiffusion are found to strongly depend on the growth temperature between 773 K and 923 K. At low T, the 3D islands are small, nearly fully relaxed and do not strain the substrate. At higher T, larger islands with significant Si content are grown, and induce deformation in the silicon substrate.
Published: 2006
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39. In situ andex situ grazing incidence diffraction anomalous fine structure study of GaN/AlN quantum dots

Author: Gilles Renaud, Vincent Favre-Nicolin, Johann Coraux, Maria Grazia Proietti, Hubert Renevier, and Bruno Daudin
Subjects: Diffraction, In situ, Nanostructure, Materials science, Grazing incidence diffraction, Scattering, business.industry, Condensed Matter Physics, Microstructure, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Optics, Quantum dot, Optoelectronics, business, Molecular beam epitaxy
Abstract: 5 pages, 2 figures, 1 table.-- PACS 61.10.Eq, 61.10.Ht, 61.10.Nz, 61.46.+ w, 68.65.Cd, 68.65.Hb, We report on a general method that takes advantage of the full capability of anomalous diffraction and can be applied to the challenging case of small size embedded nanostructures. We study in situ and ex situ GaN Quantum Dots (QDs) grown by Plasma Assisted Molecular Beam Epitaxy (PAMBE), and encapsulated by an AlN epilayer. We investigate the QD strain and composition that are related to size, morphology, and cap layer thickness by means of anomalous diffraction in grazing incidence. The X-ray energy is tuned across the Ga K-edge where the Ga atoms scattering power is strongly modified and diffraction becomes chemically selective, giving direct information on composition. Quantitative analysis of the oscillatory extended region above the edge gives information on composition and out-of-plane strain of the dots.
Published: 2006
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40. In situ investigation by GISAXS and GIXD of the growth mode, strain state and shape of Ge islands during their growth on Si(001)

Author: Marie-Ingrid Richard, E. Wintersberger, G. Bauer, Gilles Renaud, and T. U. Schülli
Subjects: Nuclear and High Energy Physics, Crystallography, Materials science, Chemical physics, Monolayer, Nucleation, Grazing-incidence small-angle scattering, Crystal growth, Small-angle scattering, Epitaxy, Instrumentation, Layer (electronics), Wetting layer
Abstract: The growth mode, strain state and shape of Ge islands were analyzed in situ, during their growth on Si(0 0 1), by combining grazing incidence small angle X-ray scattering (GISAXS) and X-ray diffraction (GIXD) measurements. GISAXS measurements provide the detailed evolution of the shape of the grown quantum dots (QDs) and allow characterizing the degree of ordering. GIXD allows monitoring the island nucleation, the evolution of the in-plane size and the epitaxial orientation of the QDs, as well as the diffusion of the wetting layer into the islands during growth. It is found that for a deposition temperature of 500 °C, an amount of about one atomic layer is transported from the four monolayers (ML) thick wetting layer into the 3D islands.
Published: 2006
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41. Structure and growth of metal on NiO(111) single crystal interfaces

Author: Gilles Renaud, M. Panabière, Antoine Barbier, Cristian Mocuta, and P. Bayle-Guillemaud
Subjects: Permalloy, chemistry.chemical_compound, Crystallography, Materials science, chemistry, Transmission electron microscopy, X-ray crystallography, Non-blocking I/O, Oxide, General Physics and Astronomy, Crystal structure, Substrate (electronics), Single crystal
Abstract: The structure, thermal stability, interfacial chemical composition, and growth parameters, derived from in situ grazing incidence x-ray diffraction (GIXD) and grazing incidence small angle x-ray scattering, ex situ atomic force microscopy, and transmission electron microscopy, of three ferromagnetic/antiferromagnetic metal/oxide interfaces [Co, Ni81Fe19 (permalloy) and Co70Fe30 on single crystalline NiO(111)] are reported. The samples were prepared in the 300–770 K temperature and 0–200 A thickness ranges. The important role of Fe in the composition and creation of the interfacial compounds as well as in the film flatness is discussed. The strong influence of the NiO(111) single crystal in determining the crystalline structure of the metal layers is evidenced. The limitations of GIXD in the description of the growth morphology were investigated in detail and are discussed with respect to the substrate crystalline quality.
Published: 2004
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42. Cubic SiC Surface Structure Studied by X-Ray Diffraction

Author: Gilles Renaud, Shirley Chiang, H. Enriquez, V. Yu. Aristov, M. D'angelo, Patrick Soukiassian, Fabrice Semond, Antoine Barbier, Lea Di Cioccio, and Thierry Billon
Subjects: Surface (mathematics), Crystallography, Materials science, Mechanics of Materials, Mechanical Engineering, X-ray crystallography, Surface structure, General Materials Science, Condensed Matter Physics
Published: 2003
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43. Ordered domain lateral location, symmetry, and thermal stability in Ge:Si islands

Author: Angelo Malachias, Gilles Renaud, Marie-Ingrid Richard, Zhenyang Zhong, Tobias U. Schülli, Vincent Favre-Nicolin, T. H. Metzger, Institut des Matériaux, de Microélectronique et des Nanosciences de Provence (IM2NP), Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), European Synchrotron Radiation Facility (ESRF), Universidade Federal de Minas Gerais [Belo Horizonte] (UFMG), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Fudan University [Shanghai], Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: [PHYS]Physics [physics], Silicon, Materials science, Physics and Astronomy (miscellaneous), Condensed matter physics, Annealing (metallurgy), Bragg's law, Crystal growth, 02 engineering and technology, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, Condensed Matter::Materials Science, Crystallography, Metastability, 0103 physical sciences, X-ray crystallography, Semiconductor Alloys, Thermal stability, Long-Range Order, Physics::Atomic Physics, Thin film, 010306 general physics, 0210 nano-technology, Layers
Abstract: International audience; Compositional atomic ordering is a crucial issue in the epitaxial growth of nanoparticles and thin films. Here, we report on a method based on x-ray diffuse scattering close to basis forbidden Bragg reflections to infer the lateral location, the symmetry, and the thermal stability of ordered domains in GeSi dome-shaped islands on Si(001) after growth and during annealing. We observe that atomic ordering does not disappear after annealing, demonstrating that it is a resilient metastable phenomenon. (C) 2015 AIP Publishing LLC.
Published: 2015
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44. Toward two-dimensional self-organization of nanostructures using wafer bonding and nanopatterned silicon surfaces

Author: Jean-Luc Rouvière, François Rieutord, K. Rousseau, Pascal Gentile, Noël Magnea, Gilles Renaud, Hubert Moriceau, Joël Eymery, F. Fournel, Denis Buttard, and F. Leroy
Subjects: Materials science, Silicon, Condensed matter physics, Wafer bonding, business.industry, Scattering, chemistry.chemical_element, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, law.invention, Condensed Matter::Materials Science, Optics, chemistry, Transmission electron microscopy, law, Quantum dot, Wafer, Electrical and Electronic Engineering, Scanning tunneling microscope, Dislocation, business
Abstract: The structure of ultrathin silicon layers obtained by molecular hydrophobic bonding is investigated. The twist and tilt angles between the two crystals are accurately controlled. The buried Si|Si interface is observed by transmission electron microscopy and by grazing incidence X-ray techniques. For low twist angle values (/spl psi/
Published: 2002
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45. Structure determination of the () reconstructed α-Al2O3(0001)

Author: Frédéric Lançon, Gilles Renaud, Igor Vilfan, and Thierry Deutsch
Subjects: Surface (mathematics), Diffraction, Materials science, business.industry, Structure (category theory), Stacking, Surfaces and Interfaces, Condensed Matter Physics, Molecular physics, Surfaces, Coatings and Films, Overlayer, symbols.namesake, Fourier transform, Optics, Beamline, Materials Chemistry, Sapphire, symbols, business
Abstract: Grazing-incidence X-ray diffraction data are combined with energy-minimization calculations to analyse the atomic structure of the Al-rich (3sqrt{3} x 3sqrt{3})R 30 deg reconstructed surface of sapphire alpha-Al_2O_3(0001). The experiments on the BM32 beamline of the ESRF provide the non-integer-order diffraction intensities and, after Fourier transform, an incomplete Patterson map. The computer simulations are implemented to obtain structural information from this map. In the simulations, the interactions between the Al overlayer atoms were described with the Sutton-Chen potential and the interactions between the overlayer and the sapphire substrate with a laterally modulated Lennard-Jones potential. We have shown that the hexagonal reconstructed unit cell is composed of triangles where the two layers of Al adatoms are FCC(111) ordered whereas between the triangles the stacking is FCC(001).
Published: 2002
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46. Self-organized growth of nanosized flat dots and vertical magnetic Co pillars on Au(111)

Author: Gilles Renaud, M. Klaua, Jeannot Mane-Mane, J.P. Deville, Jürgen Kirschner, J. Barthel, M. Noblet, O. Ulrich, Olivier Fruchart, F. Scheurer, and Antoine Barbier
Subjects: Coalescence (physics), Materials science, business.industry, Scattering, Nanotechnology, Heterojunction, Condensed Matter Physics, law.invention, Inorganic Chemistry, Quantum dot, law, Materials Chemistry, Optoelectronics, Grazing-incidence small-angle scattering, Scanning tunneling microscope, business, Spectroscopy, Molecular beam epitaxy
Abstract: We report various experiments that cast some light on the growth process of self-organized dots and vertical Co pillars on Au(1 1 1). We first report grazing incidence small angle X-ray scattering (GISAXS) on Co dots and films, that allowed us to perform a crystallographic study of the order in the self-organized array, and also yielded a statistical view of the coalescence process. We then report scanning tunneling microscopy (STM) and spectroscopy (STS) images performed during the course of vertical growth. Details about the atomic growth process and the possible influence of the growth technique used are reported.
Published: 2002
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47. Erratum: Effect of preparation on the commensurabilities and thermal expansion of graphene on Ir(111) between 10 and 1300 K [Phys. Rev. B88, 165406 (2013)]

Author: Tao Zhou, Roberto Felici, Gilles Renaud, Johann Coraux, Nils Blanc, Fabien Jean, Systèmes hybrides de basse dimensionnalité (HYBRID), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), CRG et Grands Instruments (CRG), European Synchrotron Radiation Facility (ESRF), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and CRG & Grands instruments (NEEL - CRG)
Subjects: Materials science, Condensed matter physics, Graphene, law, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Condensed Matter Physics, ComputingMilieux_MISCELLANEOUS, Thermal expansion, Electronic, Optical and Magnetic Materials, law.invention
Abstract: International audience
Published: 2014
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48. Growth of Ge islands on SrTiO3 (001) 2×1 reconstructed surface: Epitaxial relationship and effect of the temperature

Author: Gilles Renaud, Benoit Gobaut, Aziz Benamrouche, Guillaume Saint-Girons, Ludovic Largeau, Yves Robach, Jose Penuelas, Vincent Favre-Nicolin, Nils Blanc, INL - Hétéroepitaxie et Nanostructures (INL - H&N), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire de photonique et de nanostructures (LPN), Centre National de la Recherche Scientifique (CNRS), ANR-09-NANO-0013,COMPHETI,Compliance des hétérointerfaces semiconducteur/oxyde pour l'intégration monolithique d'InP sur Si(001)(2009), Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Diffraction, Materials science, Oxide, 02 engineering and technology, Epitaxy, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, Materials Chemistry, Texture (crystalline), 010306 general physics, ComputingMilieux_MISCELLANEOUS, Perovskite (structure), Condensed matter physics, business.industry, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Surfaces, Coatings and Films, Crystallography, Semiconductor, chemistry, X-ray crystallography, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, business, Molecular beam epitaxy
Abstract: The structural properties of Ge islands grown by molecular beam epitaxy on SrTiO 3 (001) substrates are investigated. We report on the effect of the temperature on the epitaxial relationship and morphology of the Ge islands. By combining X-ray diffraction measurements and atomic force microscopy we evidence a correlation between the island size and shape, the structural properties of the interface and the sample texture. In particular, we show that the growth temperature affects the nature of the interface between the semiconductor and the perovskite oxide and thus the island orientation, that evolves from fully (001) oriented to a mixture of (111) and (001) oriented islands.
Published: 2014
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49. Structure, transformation, and reduction of the polar NiO(111) surface

Author: Antoine Barbier, Gilles Renaud, and Cristian Mocuta
Subjects: Diffraction, chemistry.chemical_compound, Materials science, Condensed matter physics, Low oxygen, chemistry, Annealing (metallurgy), Air annealing, Non-blocking I/O, Oxide, Polar
Abstract: A detailed structural analysis of the $\mathrm{NiO}(111)\ensuremath{-}p(2\ifmmode\times\else\texttimes\fi{}2)$ surface by surface x-ray diffraction is presented and previous interpretations are revisited. The surface adopts the octopolar reconstruction after air annealing and a spinel-like configuration after UHV annealing under low oxygen pressure corresponding to a reduced state. The transformation rate is determined and discussed. Both configurations and their transformation allow drawing a coherent scheme of the behavior of this polar oxide surface.
Published: 2000
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50. CoO(111) surface study by surface X-ray diffraction

Author: Gilles Renaud, Cristian Mocuta, and Antoine Barbier
Subjects: Diffraction, Auger electron spectroscopy, Annealing (metallurgy), Chemistry, Spinel, General Physics and Astronomy, Surfaces and Interfaces, General Chemistry, Crystal structure, engineering.material, Condensed Matter Physics, Surfaces, Coatings and Films, Metal, Crystallography, visual_art, X-ray crystallography, visual_art.visual_art_medium, engineering, Cobalt oxide
Abstract: We present a structural investigation of the polar (111) surface of CoO single crystals by grazing incidence X-ray diffraction. The surface is found to be always covered by a ∼50 A-thick spinel Co3O4 layer that was quantitatively characterized. Attempts to remove this layer by UHV annealings or Ar+ bombardments lead to the formation of metallic Co clusters on the surface that transform again in Co3O4 by annealing under oxygen.
Published: 2000
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